This invention relates to the generation of controlled energy oscillations, and is particularly directed to a method and apparatus for the production of controlled energy oscillations, such as amplitude modulated oscillations, wherein conventional modulators are not employed.
In conventional modulation circuits of one type, carrier oscillations are generated and amplified for application to a final or power amplifier, and separate modulating circuits are provided and connected to the power amplifier circuits for amplitude modulating of the oscillations. Such circuits have relatively low efficiency, and also require a comparatively large number of elements of high current capacity.
In order to overcome the disadvantages of such modulation systems, much more efficient techniques are disclosed, i.e. in U.S. Pat. Nos. 2,445,568, (Ferguson) and 4,118,677 (Weldon). In the arrangement of these references, variable width pulses of carrier frequency were generated for application to the final amplifier, the final amplifier being essentially in the form of a switching device. As a consequence, the high power modulation devices of conventional amplifying systems were avoided.
These arrangements, however, required the production of variable width rectangular pulses, although they were not essentially the same as the pulse width modulation techniques disclosed, i.e. in U.S. Pat. Nos. 3,440,566; 3,506,920 and 3,588,744.
In the publication, "High Power Outphasing Modulation", November 1935 Proceedings of the I.R.E., H. Chireix describes a system wherein a pair of separate radio frequency channels having sine wave amplification derived an output at the power amplifier stage by varying the phase of the sine waves, in order to produce modulation as a result of variation of the phases of the sine waves from 180.degree. (for 0 output), up to 90.degree. or more, the output being combined to deliver a signal to an antenna. The system of Chireix does not, however, provide for the production of controlled energy output oscillations simply by the variation of the relative phases of waves, in accordance with the present invention.